Conveyor belts are widely used for moving minerals, coal, and a wide variety of manufactured products from one point to another. Heavy duty conveyor belts used in mining operations can extend over distances of several miles and represent a high cost component of an industrial material handling operation. Unfortunately, such conveyor belts are susceptible to damage from the material transported thereon and a rip, slit, cut or tear may develop within the belt. For instance, sharp edges of the material being transported can gouge the surface of the belt and that can result in a rip developing. Conveyor belt segments are spliced together during installation to form a continuous loop of conveyor belting. During the operation of this conveyor belt it is susceptible to damage and the integrity of the conveyor belt and these splices can be compromised and require repairs or replacement.
In order to minimize the effects of potential longitudinal rips or transverse tears due to large cord damages, mines can utilize sensors to monitor for these conditions and alert the mine to an existing or potential catastrophic event. Conveyor belts that rip longitudinally often utilize rip detection systems to contain the damage being done by the rip in order to minimize downtime. Additionally, damaged steel cords within the conveyor belt or splice defects can be monitored and repaired proactively to avoid a catastrophic event. The cost of repairing a heavy conveyor belt and cleaning up material spilled as a result of the damage can be substantial. In cases where such damage is not detected and repaired promptly, the damage can propagate as a longitudinal rip along the length of the belt or across the width of the belt as a transverse tear with continued use of the conveyor system resulting in additional conveyor belt damage and a larger downtime event for the end user. It is accordingly desirable to detect damage to the belt and to repair the damaged area of the belt before catastrophic failure occurs. By doing so the extent of the damage to the belt can be minimized, the repair can be simplified, and the spillage of material being conveyed can be reduced or avoided and the life of the conveyor belt can be extended.
Over the years, a number of systems have been developed for detecting belt damage and for automatically stopping further movement of the belt after the damage occurs. It is well known to employ antennae within conveyor belts as part of a rip detection system. In a typical system, sensors in the form of loops of conductive wire are affixed or embedded in the belt and provide a rip detection utility as part of an overall rip detection system. Rip detection is achieved through the inferential detection of an “open circuit” condition in one or more of the sensor loops in the belt. Typically, an electrical energy source external to the belt is inductively or capacitively coupled to a sensor loop in the belt. A break in the conductive wire loop of the sensor may be detected by a remote transmitter/receiver (exciter/detector). Disposition of a plurality of such sensors at intervals along the conveyor may be effected with each sensor passing within read range of one or more exciter/detectors at various locations. A rip will encounter and damage a proximal sensor loop and the existence of the tear will be detected when the proximal sensor loop damage is detected as an open circuit by the reader at its next pass. In this manner, the existence of a rip will be promptly detected and repaired with further damage to the belt being minimized.
U.S. Pat. No. 3,742,477 discloses a “figure eight” sensor loop useful within a belt sensor system. U.S. Pat. No. 3,922,661 discloses an electronic control system for conveyor belts which monitors the condition of embedded sensor conductors in the belt and provides a warning indication and/or shutdown of the conveyor when damage occurs to the belt or control circuitry.
U.S. Pat. No. 4,621,727 discloses a reinforced conveyor belt having included therein a conductor for use in a rip monitoring system, said belt comprising: (a) an elastomeric body having an upper carrying surface and a parallel lower pulley engaging surface, each surface extending indefinitely in a direction of travel of the belt; (b) a plurality of reinforcement layers positioned within said elastomeric body; (c) a plurality of envelopes of low coefficient of friction material positioned within said elastomeric body and spaced apart in the direction of travel of the belt, wherein each envelope establishes a void area in said elastomeric body within said envelope; and (d) a shaped conductor positioned within said envelope such that said conductor is free to move within said void area during operation of said reinforced conveyor belt.
U.S. Pat. No. 4,854,446 discloses “figure eight” sensor loops disposed at intervals along a conveyor belt. This reference more specifically reveals an endless conveyor belt having a direction of travel comprising: (a) an elastomeric body having a load carrying surface and a parallel pulley engaging surface; (b) a reinforcement ply disposed within said elastomer body; and (c) a conductor, disposed within said belt in a predetermined pattern forming a closed current path; and wherein said conductor comprises a plurality of strength filaments or strands of a first metal wrapped about a conductive core of a second metal, said strength filaments or strands having a higher fatigue resistance than the conductive core, for increasing the fatigue resistance of the conductive core.
U.S. Pat. No. 6,352,149 provides a system in which antennae are embedded in a conveyor belt to couple with an electromagnetic circuit consisting of two detector heads and an electronic package. Coupling occurs only when an antenna passes across the detector heads and can only occur when the loop integrity has not been compromised. U.S. Pat. No. 6,352,149 more specifically reveals a conveyor belt incorporating within it a rip detection sensor comprising a conductor formed in an endless loop arranged in a signal inverting configuration wherein the conductor crosses itself in at least one crossing place, characterized in that: the conductor is formed as microcoil springwire; the conductor crosses itself by crossing through itself such that the microcoil springwire resides substantially in a single plane throughout the sensor including the crossing places; and means for preventing short-circuiting of the conductor at the crossing places.
U.S. Pat. No. 6,715,602 discloses a conveyor belt incorporating within it a rip detection sensor comprising a conductor formed in an endless loop, characterized in that: the belt includes at least one transponder secured to the belt in coupled relationship with the conductor; and the transponder transmits information identifying the location of the conductor along the belt.
U.S. Pat. No. 6,988,610 discloses an inspection system for detecting and reporting conditions of a conveyor belt, the system comprising: a controller comprising a splice detection program for receiving image data from at least one camera structured and arranged to capture an image of a portion of a conveyor belt, for detecting a splice in the image of the portion of the conveyor belt by processing the received image data, and for generating status information associated with the portion of the conveyor belt based on a detected splice.
International Patent Publication No. WO 2007/026135 A1 reveals a system for monitoring operation of a conveyor belt installation which comprises a conveyor belt having steel or other relatively magnetically permeable reinforcing material, said system comprising a field generator arranged in proximity to the conveyor belt to generate a magnetic field, a sensor unit arranged in proximity to the conveyor belt at a position downstream from the field generator as considered in a normal direction of belt movement, said sensor unit sensing the magnetic field emanating from the passing conveyor belt, and monitoring means to receive data related to the magnetic field properties sensed by the sensor unit during a plurality of passages of each of the length of the conveyor belt past the sensor unit, said monitoring means incorporating comparison means to compare a subsequently received set of data with an earlier received set of data, and output means to provide an output signal representative of reinforcement damage or deterioration when subsequently received data has departed from earlier received data by more than a prescribed extent.
U.S. Pat. No. 7,740,130 and U.S. Pat. No. 7,942,258 disclose a digital processor for use in a conveyor belt rip detector, which provides excitation signals at a selected frequency to inverted and non-inverted sensor loops on a conveyor belt and then, detects corresponding received signals from the sensor loops. The digital processor then performs FFTs on the corresponding received signals to provide respective received signal frequency spectrums. Next magnitude and phase values of the selected frequency in the respective received signal frequency spectrums are used to determine a qualitative state of the sensor loops. The selected frequency has a lowest detected ambient noise level, and the magnitude value is a normalized magnitude value. These patents more specifically reveal an apparatus for use in a conveyor belt rip detector that couples excitation signals to sensor loops carried by a conveyor belt and thereafter, detects corresponding received signals from respective sensor loops, the apparatus comprising: an excitation frequency generator generating excitation signals at a first frequency, the excitation signals adapted to be transmitted to the sensor loops, an analog-to-digital converter adapted to detect corresponding received signals from the sensor loops, a fast Fourier transform analyzer adapted to perform fast Fourier transforms on the corresponding received signals to provide respective signal frequency spectrums, and loop state logic determining magnitude and phase values for the first frequency in the respective received signal frequency spectrums and determining loop present and loop not present states of the sensor loops in response to determining the magnitude and phase values.
U.S. Pat. No. 7,810,634 and U.S. Pat. No. 8,256,607 disclose a monitoring system is provided for a moving conveyor belt having a plurality of embedded reinforcing cords and identification tags. A tag reader detects and identifies the identification tags passing by the tag reader while a belt monitor scans the cords to detect a plurality of magnetic reference points and a damage event of at least one cord. A control unit in communication with the belt monitor and the tag reader analyzes the belt monitor to identify the plurality of magnetic reference points and the damage event. The control unit also acquires a belt location on the moving conveyor belt from a belt map based on the detected and identified identification tag and a magnetic reference point from the plurality of magnetic reference points. When a damage event is identified, a location of the damage event is determined by the control unit based on the acquired belt location.
U.S. Pat. No. 7,894,934 discloses a remote conveyor belt monitoring system for monitoring an operation of a conveyor belt at a first geographic location. A local HMI is operable to acquire and store data representing conveyor belt conditions and operating characteristics. First and second computers at different geographic locations acquire the data via an internet. Thus, data relating to the operating conditions of the conveyor belt can be remotely consolidated and monitored by computers at different global locations. This patent more specifically reveals a method of remotely monitoring multiple conditions of a plurality of conveyor belts using a web-based diagnostic and predictive system that permits an automatic comprehensive collection and consolidation of data relating to conveyor belt health comprising: sensing conditions relating to a first operating conveyor belt at a first geographic location; generating at the first location first data in response to the conditions sensed; storing the first data in a first database at the first geographic location; acquiring the first data with a monitoring computer at a monitoring location geographically remote from the first geographic location; storing the first data in a monitoring database at the monitoring location; sensing conditions relating to a second operating conveyor belt at a second geographic location; generating at the second location second data in response to the conditions sensed; storing the second data in a second database at the second geographic location; acquiring the second data with said monitoring computer at said monitoring location geographically remote from the first and second geographic locations; storing the second data in the monitoring database at the monitoring location.
U.S. Pat. No. 8,069,975 discloses a conveyor belt rip detection system with belts having rip detection inserts that can be more easily integrated into conveyor belts at low cost. These rip detection inserts do not adversely affect the durability of the conveyor belt and can be easily replaced in the event of belt damage. This rip detection system also provides a highly reliable early image of belt damage that can facilitate quick repair before extensive belt damage occurs. U.S. Pat. No. 8,069,975 more specifically discloses a conveyor belt comprising (1) an elastomeric body having a load carrying surface and a parallel pulley engaging surface; (2) a reinforcement ply disposed within the elastomeric body; and (3) a multitude of rip detection inserts, wherein the rip detection inserts are spaced along the longitudinal length of the conveyor belt, wherein the rip detection inserts contain a multitude of rip detection wires that are comprised of a magnetically permeable material, wherein the rip detection wires are aligned in the rip detection inserts at a bias angle of 15° to 75° from being perpendicular to the longitudinal direction of the belt, and wherein the rip detection wires are spaced incrementally across the width of the belt.
Prior art rip detection panels generate issues that can either affect the integrity of the belt or the ability to replace damaged loops. Rip detection panels with wires running transversely to the conveyor belt are desirable from a manufacturing standpoint. However, such rip detection panels generate undesirable flexural properties that can result in premature failure of the conveyor belt. In any case, including rip detection loops or rip detection panels into a conveyor belt complicates the manufacturing process and adds cost to the conveyor belt. Additionally, such rip detection loops and rip detection panels do not monitor for damage in conveyor belt splices. There is accordingly a need for a reliable system to monitor for damage in conveyor belt splices. It would be even more desirable for such a system to be capable of monitoring conventional conveyor belts which do not include rip detections loops or rip detection panels. Such a system would not add additional cost to the conveyor belt per se and would not compromise the durability of the conveyor belt.